Passive battery discharge device

Abstract

A passive battery discharge apparatus located within a cap. The cap extends over battery contacts to be discharged. The discharge apparatus includes a conductive material with specified volumetric resistivity properties that is formed into a pad. The cap is positioned over the contacts so that the pad touches and spans between the contacts to be discharged. A spring insures good contact between the pad and the battery contacts. A metal heat sink provides added thermal control. The discharge apparatus provides an economical solution to safely transport batteries that are beyond their useful service life by avoiding circuit components in favor of conductive elastomers or conductive foams.

1. An apparatus for discharging a battery having contacts comprising:
 a discharge cover having a cap formed therein to define a discharge apparatus receiving zone; and 
 a passive battery discharge apparatus disposed within the cap's receiving zone including a conductive material having a spongy consistency, wherein said conductive material is physically configured as a direct contact spanning pad to resiliently press on to the battery contacts, and wherein said conductive material is electrically configured as a non-switched compressible element to passively and safely discharge the battery. 
 
     
     
       2. The apparatus of  claim 1 , wherein said passive battery discharge apparatus further includes a resilient member which exerts a biasing force on said conductive material in a direction out of the cap's receiving zone. 
     
     
       3. The apparatus of  claim 1 , wherein said passive battery discharge apparatus further includes a heat sink in contact with said conductive material, wherein said heat sink passively dissipates heat generated during battery discharge. 
     
     
       4. The apparatus of  claim 3 , wherein said passive battery discharge apparatus further includes a resilient member; wherein said heat sink is disposed between said resilient member and said conductive material; whereby said resilient member exerts a biasing force on said heat sink which is distributed over the surface of said conductive material in a direction out of the cap's receiving zone. 
     
     
       5. The apparatus of  claim 1 , wherein said conductive material has an electrical conductance as measured by volume resistivity in the range of about 100 to about 100,000 ohms·cm. 
     
     
       6. The apparatus of  claim 5 , wherein said conductive material includes a conductive foam. 
     
     
       7. The apparatus of  claim 5 , wherein said conductive material includes a conductive elastomer. 
     
     
       8. The apparatus of  claim 3 , wherein said heat sink is made from metal and the conductive material is made from one of conductive elastomer and conductive foam. 
     
     
       9. The apparatus of  claim 3 , wherein the cap includes an open proximal end and a closed distal end, wherein said resilient member is disposed within the closed distal end with the heat sink installed at the open proximal end of the cap to compressingly retain said resilient member therein. 
     
     
       10. The apparatus of  claim 1 , wherein said discharge cover includes a securing device for locking the cover to the battery. 
     
     
       11. An apparatus for passively discharging a battery having contacts comprising:
 a discharge dome to enclose the contacts of the battery to be discharged; and 
 a conductive pad disposed within said discharge dome for directly contacting each contact and spanning across said contacts, wherein said conductive pad is made from a material selected from the group consisting of a conductive elastomer, a conductive foam, and combinations thereof; 
 wherein said conductive pad comprises a passive discharge device that is devoid of switches, wires and resistors. 
 
     
     
       12. The apparatus of  claim 11 , wherein said passive discharge device consists of said conductive pad. 
     
     
       13. The apparatus of  claim 11 , further comprising a metal heat sink that is thermally coupled to said conductive pad. 
     
     
       14. The apparatus of  claim 13 , wherein said passive discharge device consists of said conductive pad and said heat sink. 
     
     
       15. The apparatus of  claim 11 , further comprising a spring disposed within the discharge dome for exerting a biasing force against said conductive pad. 
     
     
       16. The apparatus of  claim 15 , wherein said passive discharge device consists of said conductive pad and said spring. 
     
     
       17. The apparatus of  claim 13 , further comprising a spring disposed within the discharge dome for exerting a biasing force against said heat sink and wherein said passive discharge device consists of said conductive pad, said heat sink and said spring.